A. Field of the Invention
The invention relates generally to the field of three dimensional modeling and animation. In particular, the invention relates to an improved three dimensional modeling and animation system having an object oriented architecture.
B. Related Art
Three dimensional modeling systems allow users to generate models of three dimensional objects using computers. In previous systems, a user defines a simple three dimensional (3D) object and then applies various transformations and manipulations (e.g., stretch, bend) to that object. The transformations and manipulations change the way the object looks. However, the modifications, once made, are difficult to change. For example, a user first defines a shape such as a sphere. To change the look of the sphere, the user applies some type of function to that sphere. For example, the user might stretch the sphere in one direction by scaling the sphere. Similarly, the user might apply some type of twisting function to the sphere. If the user wanted to change the amount of stretching, the user first undoes the twist, undoes the stretch (removes the scaling), and then re-scales the sphere. The user must then reapply the twist. Thus, it is difficult for the user to change the scaling of the sphere without affecting the twisting operation.
Therefore, it is desirable to have a 3D modeling system that is simpler for the user to use by allowing the user to make changes to a modification of an object without having to undo all of the modifications made subsequent to the modification of interest.